It is known to coat fabrics with coatings, e.g. polymer coatings, for the purpose of protecting the fabric from wear such as that experienced during everyday use or during repeated wash cycles.
Prior art methods of depositing the coatings describe polymerising fluorocarbon gas precursors such as tetrafluoromethane (CF4), hexafluoroethane (C2F6), hexafluoropropylene (C3F6) or octafluoropropane (C3F8) using plasma deposition techniques. Other precursor monomers such as fluorohydrocarbons, e.g. CF3H or C2F4H2 or fluorocarbonethers such as CF3OCF3 or long chain acrylates or methacrylates having perfluorocarbon chain lengths of eight carbons or more, such as 1H,1H,2H,2H—heptadecafluorodecyl acrylate (FC8), are also described in the prior art.
However, these particular classes of precursor molecules require high power plasma or pulsed plasma in order to initiate the polymerisation reaction. Moreover, such precursor molecules may also require high precursor gas flow rates and long deposition times in order to obtain an acceptable thickness of the polymer layer.
A problem that may arise when using high precursor gas flow rates and/or high power or pulsed plasma is that the resultant polymer coatings may have a non-uniform thickness. For instance, high power plasma causes monomers to fragment which can result in unpredictable deposition of the polymer and hence substandard coatings.
Another problem that may arise when utilising fluorocarbon gas precursor molecules such as those described above is that the subsequently formed polymer layer has limited hydrophobicity and oleophobicity. Typical contact angles for water that can be achieved with such coatings are maximum 90 to 100°. The resistance to oil is also limited to maximum level 3 to 4 according to ISO14419.
Another problem is that acrylates and methacrylates having perfluorocarbon chain lengths of eight carbons or more may contain significant levels of the hazardous, carcinogenic, chemical perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), which have been the recent subject of investigation into adverse health effects of humans.